SpringerLink
Forum Springer Astron. Astrophys.
Forum Whats New Search Orders


Astron. Astrophys. 323, L25-L28 (1997)

Previous Section Next Section Title Page Table of Contents

1. Introduction

Water vapour, one of the first molecules observed in radio astronomy, was discovered in 1962 by Cheung et al. through the maser emission of its 616 -523 rotational transition at 22 GHz. Since then, many lines of H2 O have been observed at submillimeter wavelengths from the ground. However, all these lines are masering which renders the interpretation of the data difficult (Cernicharo et al. 1990; Menten & Melnick 1991). Recently, Cernicharo et al. (1994, 1996) and González-Alfonso et al. (1995) have mapped the H2 O 183.3 GHz transition in three star-forming regions (Orion-IRC2, HH7-11, and W49N) providing the first evidence that the distribution of water vapour is extended and that the H2 O abundance can be larger than 10-5 in warm molecular clouds.

In this Letter, we present further evidence that water vapour is extended in molecular clouds based on the detection of far-infrared H2 O transitions seen in absorption against the continuum of the SgrB2 molecular complex.

Previous Section Next Section Title Page Table of Contents

© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998

helpdesk.link@springer.de